An upper level ridge shifted into the Interior Mountain West from the eastern Pacific during the period between the 9-14th, keeping temperatures above normal during this time. According to the Maricopa County Department of Public Health, 22 heat-associated fatalities occurred during this time.
Every event with a place to put it; 11 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PSR wrote it up.
An upper level ridge shifted into the Interior Mountain West from the eastern Pacific during the period between the 9-14th, keeping temperatures above normal during this time. According to the Maricopa County Department of Public Health, 22 heat-associated fatalities occurred during this time. Additionally, two heat-associated fatalities occurred in La Paz County during this event.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Phoenix, AZ wrote its last area forecast discussion before the first event at Aug 8, 10:10 PM MST, 1 hour 50 minutes earlier.
Area Forecast Discussion
National Weather Service Phoenix AZ
1010 PM MST Tue Aug 8 2023
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
Monsoonal moisture will lead to continued rain chances of 10 to 30
percent on the lower deserts and 30 to 50 percent over the higher
terrain through Thursday. A gradual decline will take place from
west to east beginning Friday with storm chances limited to south-
central Arizona. Anticipate high temperatures to be lower than they
have been in several weeks but still near, to slightly above,
normal. A warming trend is anticipated for early next week with
highs climbing above 110 at most lower desert locations by next
Tuesday.
&&
.DISCUSSION...
Deep southwesterly flow remains in place which is aiding coherent
storm movement to the northeast. The development areas have been
over higher terrain locales of the eastern third of AZ plus Pima
County west of Tucson. With the storm movement to the northeast, it
will be hard to get storms to advect to our forecast area. However,
outflow from Pima County storms could aid propagation to the north.
Latest aircraft soundings indicate there isn't a lot of CIN over the
Phoenix area. We may wind up having something of a repeat of last
night/this morning with a passing disturbance tapping into the
convective potential. This time, the models are picking up on a weak
short wave emanating from the upper trough where the remnant
circulation of former TS Eugene is. There is also a moisture
convergence boundary over the Mohave Desert that is over/near our
CWA border with VEF CWA. That boundary is anticipated to nudge
further north and may be another aid to convection. Most of the
deterministic CAMs are depicting relatively weak echoes/showers late
tonight - mainly over VEF and FGZ CWAs. The HRRR has had run- to-run
variations in showing very isolated storms over La Paz County with
better coverage just north. The NBM PoPs once again has a late
night/morning peak over the whole forecast area (except for portions
of Gila County which peak this afternoon/eve). That being said, the
numbers aren't overwhelmingly high but definitely higher than
seasonal climatology. Though not convection related, model data
shows strong winds for late afternoon and tonight over western
portions of Imperial County extending into the Imperial Valley.
Thus, a Wind Advisory was issued.
The convective outlook for later Wednesday has a lot of uncertainty.
The moisture availability will be relatively good. But, being on the
back side of the disturbance, there may be some subsidence to hinder
things. Also, where/if there is prior precip, that will hinder
destabilization as well. But, if the preceding wave isn't much, then
potential will be better. Global models are depicting a gradual
downtrend in moisture availability beginning Thursday but not a
dramatic drop off. The NBM PoPs reflect this with an eastward
retreat - most noticeable on Friday - but lingering over south-
central AZ through next Tuesday.
Temperatures are expected to be within a few degrees of normal for
the next several days thanks to the influence of troughing and
eastward retreat of the strongest high pressure. But, that still
means moderate HeatRisk as opposed to no issues at all. Early next
week, the ridge slowly expands westward again leading to an uptrend
in temperatures - potentially back to excessive thresholds by next
Tuesday. Of note, the NBM deterministic value for next Tuesday is at
the 75th percentile.
&&
.AVIATION...Updated at 0510Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No significant weather impacts should exist though Wednesday night
under occasional mid/high cloud decks. Forecast confidence with
respect to overnight wind shifts is lower than normal as a distant
outflow has already moved into the metro. Directions may remain S/SE
for the remainder of the night, but could briefly oscillate to the
back to the SW before finally settling on easterly by sunrise.
Otherwise, west winds with a few higher gusts should be common again
Wednesday afternoon. Models suggest distant traveling outflows
Wednesday evening will result in an earlier than usual shift to an
easterly component.
Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty winds will be the greatest weather issue under periods of
mid/high cloud decks. At KIPL, winds should relax later tonight,
however strong wind gusts 20-30kt will return Wednesday evening with
some lofted dust. Overall, wind directions will tend to stay
westerly through the period. Directions at KBLH should vary more
between SE and SW with afternoon gusts more muted in a 20-25kt
range.
&&
.FIRE WEATHER...
Monsoonal moisture will linger through Thursday for ongoing, though
modest, potential for thunderstorms at any given location. High
temperatures will be at, or a few degrees above, normal. MinRH
values will be in the 20-30% range and MaxRH values in the 40-60%
range most places. Eastern Riverside County will see the most
significant increases in humidity. Late in the week and over the
weekend, anticipate a gradual decline of humidity as well as storm
chances. Temperatures trend upward early next week to well above
normal. Apart from thunderstorms, winds will favor familiar warm
season patterns - except over Imperial County with late afternoon
and nighttime windiness from the west today and Wednesday.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 8 AM PDT Wednesday for CAZ562.
Wind Advisory until 2 AM PDT Wednesday for CAZ563-566-567.
&&
DISCUSSION...AJ
AVIATION...18
FIRE WEATHER...AJThe national radar mosaic for the moment the first event began.
11 heat. Local standard time, as filed.
Seven heat-associated fatalities (2 direct and 5 indirect) were reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
Two direct fatalities were reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
One direct fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
One direct fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
One direct fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
One direct fatality was reported in La Paz County, with their details, such as age, gender, circumstances, and exact location unavailable.
One direct fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
Four heat-associated fatalities (2 direct and 2 indirect) were reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
Three heat-associated fatalities (1 direct and 2 indirect) were reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
Two heat-associated fatalities (1 direct and 1 indirect) were reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances, and exact location unavailable.
One direct fatality was reported in La Paz County, with their details, such as age, gender, circumstances, and exact location unavailable.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Heat, Central Phoenix | 2023-08-09 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-09 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-09 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-09 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-09 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-09 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-09 | Unknown | Indirect | ||
| Heat, East Valley | 2023-08-09 | Unknown | Direct | ||
| Heat, East Valley | 2023-08-09 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-10 | Unknown | Direct | ||
| Heat, North Phoenix/Glendale | 2023-08-10 | Unknown | Direct | ||
| Heat, East Valley | 2023-08-10 | Unknown | Direct | ||
| Heat, Central la Paz | 2023-08-10 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-11 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-12 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-12 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-12 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-12 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-13 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-13 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-13 | Unknown | Indirect | ||
| Heat, Central Phoenix | 2023-08-14 | Unknown | Direct | ||
| Heat, Central Phoenix | 2023-08-14 | Unknown | Indirect | ||
| Heat, Central la Paz | 2023-08-14 | Unknown | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2023Every state in 2023This day in weather historyWarnings in Arizona, August 2023
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1213337, 1213338, 1213339, 1213340, 1213341, 1215521, 1213342, 1213343, 1213344, 1213345, 1215523.